Let me jump right in. First of all you need the standard equipment for PHP, an IDE like XAMPP and an editor like PHP EDITOR 2OO7.
Were going to make a simple guestbook using three files, webpage.php, shout.php and shout.txt.
Webpage.php can be changed to whatver you want, it will be the page on which the guestbok is shown, you could even use this code and add it to another php page n your site. Shout.php is the proccessing page and shout.txt is where the shouts are stored.
Firstly we need to make the visual design of the box. Mine is very simple, like the one here at T17 just a big box for the text and two more boxes for your name and message. I wont go into the HTML code for this form as im concentrating on the PHP so here is the HTML code for the form:
CODE
<?
echo”
<HTML>
<center><BR><BR><BR>
<form action=shout.php method=post>
<textarea name=shouts rows=7 cols=65>
</textarea>
<BR>
<input type=text name=name value=name> -- <input type=text name=shout value=Message>
<BR>
<input type=submit value=submit>
</form>
“;
?>
echo”
<HTML>
<center><BR><BR><BR>
<form action=shout.php method=post>
<textarea name=shouts rows=7 cols=65>
</textarea>
<BR>
<input type=text name=name value=name> -- <input type=text name=shout value=Message>
<BR>
<input type=submit value=submit>
</form>
“;
?>
We will go back to this code later but for now just use ECHO or PRINT to show this text to the user in the first PHP file, the one you want the shoutbox to appear on. Now were going to look at the shout.php processing page.
The first thing to do is to get the variables from the form, as we used the POST method we will need to use this array when getting the values in php.
As you might know to get a value from the POST variable into another variable the code looks like this:
CODE
$shoutname = strip_tags($_POST['name']);
$shouttxt = strip_tags($_POST['shout']);
$shouttxt = strip_tags($_POST['shout']);
So now whatever the user put into the boxes is now contained in the two variables called SHOUTNAME and SHOUTTXT to use later on. Note i used STRIP_TAGS to make the data more safe. As were storing the data as a text file any code wont get run anyway but this is just a precaution, i had someone try to inject code into my shoutbox and it didn't work even without the strip_tags so its fairly safe anyway.
Now we have the data we need to play with it meaning we need to store it somewhere, we could use a database but why bother? I think that's only useful in you need to hide the contents of the shoutbox or if you plan on getting thousands of shouts because the file would get very large with thousands of messages in it. I didnt plan n getting this many shouts so a file based one was fine for me and that is the route this tutorial will follow!
To write to a file we need three functions, FOPEN, FWRITE and FCLOSE, fairly easy to understand, they open, write to, and close files respectively. But before we write everything to a file we need to reverse the text, this is so that the latest shouts end up at the top of the shoutbox, otherwise it would be very annoying to scroll down to see the last shout. And before we reverse the string we first need to make it. We want the messages to look like this:
QUOTE
--------------------------------
Name: my name
Message: my message
--------------------------------
Name: my name
Message: my message
--------------------------------
to arrange this using PHP we can do something like this:
CODE
$shoutn = "$shoutname : \n $shouttxt \n --------------------------------------------------------------- \n";
So now we have arranged the text we need to reverse it using STRREV:
CODE
$shout = strrev($shoutn);
Now you might have realised by now that all the text is also back to front and unreadable, but thats not a problem as we will be reversing it again shortly which is when it will become readable again.
Now we can get back to the file functions of opening, writing and closing. First we use FOPEN to open the file, FOPEN returns what is called a “handle” which is sort of a reference to the file and to use this handle we need to assign it to a variable:
CODE
$handle = fopen(“shout.txt, "ab");
This code opens the file”shout.txt” in APPEND mode which means we can write to the file and it will be written at the end of the file.
Now we need to write to the file using FWRITE, this is where we use the $handle variable to reference the file we want to write to, in this case “shout.txt”:
CODE
fwrite( $handle, $shout );
See how the handle comes first to let PHP know where we want to write and then the variable $shout, which we said earlier is the reversed version of the user's input, which is what must be written. So now the data is saved in the file and we have to close the file or we wont be able to open it again the next time they leave a message. We use FCLOSE for this, and again we use the $handle variable to let it know what to close:
CODE
fclose($handle);
Now that is pretty much the end of the PHP file except the user can only see a blank screen by now so we need to redirect them, After friiks replied with some useful code i have edited this line and came up with this:
CODE
header("Location: ".$_SERVER['HTTP_REFERER']);
?>
?>
The header function in php can be used so long as it is the first line of outputted text, this means that if there is an ECHO or PRINT command above it anywhere it will not work but in this script we dont have any ECHOs or PRINTs so we can use a header as friiks said. The "location: ".$_SERVER['HTTP_referer'] simply means "go back to the last page" and so we are taken back to whichever page we entered out shout.
Now for the final additions to the first page we wrote because otherwise we will never see the shouts made already.
Again we will be using FOPEN and FCLOSE but this time we will also be using FREAD to read the file and get its contents. So open the first file which i called webpage.php it should already have the starting tag for php “<?” On the line under this tag, above the ECHO and html parts we need to use FOPEN, FREAD and FCLOSE. First of course FOPEN in the same way as before:
CODE
$handle = fopen(“shout.txt, "rb");
Now we need to use FREAD, its another simple tag that uses the $handle variable again but it also needs another variable which is the size of the file, this is so it knows how much data it needs to read, of course WE dont know the size but PHP does and by using the function FILESIZE we can find out the size of our file and give that value to FREAD:
CODE
$contents = fread($handle, filesize(“shout.txt));
Not how we used another variable, $contents, this variable now contains all the data from our shout.txt file which is of course, all the shouts made by our users. Now we need to close the file, easy enough:
CODE
fclose($handle);
if you remember back a bit we reversed the contents of that file so now in the $contents variable we have a load of back to front text that is useless, unless of course we reverse it again, which is what we are going to do:
CODE
$text = strrev($contents);
so now the text should be the right way round and with the last shout at the top. Hopefully!
So now we just need to get this text into the textbox we made on the first page. As its a TEXTAREA this is really easy!!! WE just need to put $text inside the textarea, so edit the textarea code so it looks like this:
CODE
<textarea name=shouts rows=7 cols=65>
$text
</textarea>
$text
</textarea>
And bingo!! We are done! An important note is that PHP does not like empty files so the file “shout.txt” will always need something in it, a normal SPACE “ “ is enough, or even just a newline. Also you might need to refresh the first page to see your shout in the shoutbox, i suspect this can be solved with JavaScript but im not very good with JS so if you are then reply and let us all know how to solve that problem!
Otherwise, enjoy this tut. Ive attached my versions of what i wrote just so you can check if you went wrong! You might have trouble if you just copy and paste my code as i wrote it in open office and i had a problem with the quote marks myself so if it doesnt work try copying by hand and if it still doesn't work then drop me a line
NOTE my version of "webpage.php" is "index.php" in the attachments and i didn't attach the shout.txt file as its simply a text file with one space in it.
EDIT** minor edit to solve a problem in IE, added an extra "\n" to the string which is saved to the file. Also edited thanks to Friiks as below
